Which of the following is a characteristic of all rocks? choose one: a. they have a definable chemical composition. b. they are a collection of minerals or a body of glass. c. they must contain quartz. d. they can be manufactured for commercial use.

The correct answer is B. They are a collection of minerals or a body of glass.

Explanation:

The study of rocks needs the observation of their characteristics; its characteristics depend on the properties of the minerals that compose it, its relative amounts and the way in which these were joined to originate the rock. Texture is the external appearance of any rock. It depends on the shape, size and internal arrangement of mineral crystals. Each of these characteristics maintains its specific properties (chemical and physical) in the rock as a whole.

In a rock we can distinguish two types of minerals:

Essential minerals. They are the ones that constitute the nature of the rock and give it its characteristics and properties for being in greater proportion. The lack of one of them would result in the formation of a different rock with different properties.

Accessory minerals These are minerals that appear occasionally in very low proportions within the typical composition of a particular rock. Its presence does not alter the basic characteristics of the rock.